The present invention relates to a side sliding door apparatus having right and left sliding doors for opening and closing a side entrance of a railcar.
For protecting passengers in a railcar, a side sliding door apparatus is required to have a high operational reliability without any accidental operation while the railcar is running or staying stationary. To satisfy this requirement, the inventors of the present invention have developed a side sliding door apparatus for an electric railcar disclosed in Japanese Patent Publication (KOKAI) No. 2000-142392. According to the publication, the side sliding door apparatus is provided with one actuator for two sliding doors, and the actuator opens/closes and locks/unlocks the sliding doors.
FIG. 9 to FIG. 12 show the side sliding door apparatus for the electric railcar disclosed in the patent publication, and a brief description thereof will be given. FIG. 9 is a side view showing an entire structure of the side sliding door apparatus for the electric railcar, and FIG. 10 is an enlarged view showing essential parts thereof. In FIGS. 9 and 10, two sliding doors 1 and 2 are movably suspended from a door rail 3, which is mounted horizontally along a side of the electric railcar via moving bodies 4. The sliding doors 1 and 2 are capable of moving horizontally in reverse directions to open and close an entrance of the electric railcar. The sliding door 1 at the left side in FIG. 9 is driven by a linear motor 5 as an actuator connected to the moving body 4 of the sliding door 1. As shown in FIG. 10, a movable element 5a of the linear motor 5 is connected to the moving body 4 such that the movable element 5a can slide by a predetermined distance x in opening and closing directions (in the horizontal direction in FIG. 10). A compression spring 6 is interposed between the movable element 5a and the moving body 4. With this arrangement, the movable element 5a can freely move relative to the sliding door 1 by the predetermined distance x in the opening direction of the sliding door 1.
On the other hand, the sliding door 2 at the right side is moved along with a motion of the sliding door 1 via a direction changing mechanism 7. As shown in FIG. 10, the direction changing mechanism 7 is comprised of a lower rack 9 connected to the moving body 4 of the sliding door 1 via a connecting rod 8, an upper rack 11 connected to the moving body 4 of the sliding door 2 via a connecting plate 10, and a pinion 12 engaging the racks 9 and 11 at the same time. The lower rack 9 and the upper rack 11 are guided in a unit case 7a fixed on the railcar side such that they can slide in the opening and closing directions. A shaft fixed on the unit case 7a supports the pinion 12. The direction changing mechanism 7 changes a moving direction of the sliding door 1 driven by the linear motor 6 and transmits the motion to the sliding door 2.
FIGS. 11 and 12 show details of a locking mechanism 13 arranged at a side of the direction changing mechanism 7 (in FIG. 9), as well as a push rod 14 and a pull fitting 15 for causing the locking mechanism 13 to lock and unlock the sliding doors 1, 2. FIG. 11 shows a state in which the locking mechanism 13 locks the sliding doors 1, 2. FIG. 12 shows a state in which the locking mechanism 13 unlocks the sliding doors 1, 2. In FIGS. 11 and 12, the push rod 14 and the pull fitting 15 are mounted on the movable element 5a of the linear motor 5. The push rod 14 is fixed horizontally, and the pull fitting 15 with a hook end is placed over an upper surface of the push rod 14 and is connected to the push rod 14 to rotate vertically by a pin at one end. The pull fitting 15 is forced upward by a compression spring 16 interposed between the pull fitting 15 and the push rod 14, and is restricted in an upward rotational range by a headed pin 17 that loosely penetrates the push rod 14 to be screwed into the pull fitting 15. A guide fitting 18, which is arranged to contact an upper surface of the pull fitting 15 to limit the pull fitting 15 from rotating upward, is fixed at a front end of a frame of the linear motor 5.
The locking mechanism 13 is comprised of a vertical latch rod 22 guided in a guide cylinder 21 supported and fixed by the unit case 7a to slide in an axial direction, a latch plate 23 integrated with a head of the latch rod 22, and a lock spring 24 comprised of a tension spring for urging the latch rod 22 downward. For moving the locking mechanism 13 with the sliding door 1, the locking mechanism 13 is comprised of a slider 19 guided to slide in a moving direction of the sliding doors 1, 2, and a back spring 20 comprised of a compression spring for urging the slider 19 toward the sliding door 2. A cam surface 19a comprised of an inclined step is formed at an upper side of the slider 19. An engagement protrusion 19b is provided at an end of the slider 19. A roller 25 contacting the cam surface 19a of the slider 19 is rotatably mounted on the latch rod 22 via an attachment fitting (not shown). The lock spring 24 is extended between the latch plate 23 and the unit case 7a for urging the latch rod 22 downward. As described later, the latch rod 22 moves up and down in response to the opening and closing motions of the sliding doors 1, 2.
FIG. 11 shows a state in which the sliding doors 1, 2 are locked in a closed state in the above described side sliding door apparatus. In this state, an end of the latch rod 22 is inserted into the latch hole 26 of the upper rack 11 constituting an engagement section of the direction changing mechanism 7 to lock the sliding motion of the upper rack 11. Thus, the sliding doors 1, 2 connected to the upper rack 11 can not move.
Further, in this state, the push rod 14 is brought into contact with the engagement protrusion 19b of the slider 19, and the hook portion of the pull fitting 15 is engaged with the head of the engagement protrusion 19b with an inclined surface. When an opening instruction is given in this state, the movable element 5a of the linear motor 5 moves leftward. At an initial stage of this movement, the movable element 5a moves leftward by a predetermined distance x with compressing the compression spring 6 while leaving the sliding door 1 in a closed position. In the meantime, the pull fitting 15 pulls the slider 19 via the engagement protrusion 19b. At this moment, the pull fitting 15 tries to rotate upward due to the urging force of the compression spring 16 and the action of the inclined surface of the head of the engagement protrusion 19b, but can not rotate because the guide fitting 18 presses the pull fitting 15.
When the slider 19 is pulled leftward, the roller 25 is pushed up onto the upper surface of the slider 19 via the inclined plane of the cam surface 19a. This causes the latch rod 22 to be lifted and pulled out the latch hole 26 to release from the upper rack 11, thereby unlocking the sliding doors 1, 2. When the movable element 5a moves for almost the predetermined distance x, the pull fitting 15 is released from the guide fitting 18. As a result, the pull fitting 15 is rotated upward by the urging force of the compressing spring 16 and is released from the engagement protrusion 19b of the slider 19. Even when the pull fitting 15 is released, the slider 19 remains in an advancement position due to the urging force of the back spring 20 and keeps the roller 25 pushed up.
Then, the movable element 5a moves the sliding door 1 leftward up to a predetermined full-open position. Accordingly, the sliding door 2 moving along the sliding door 1 via the direction changing mechanism 7 moves rightward, so that the sliding doors 1, 2 are opened. The sliding door 1 then moves rightward in response to a closing instruction, and when the sliding door 1 reaches the closing position in FIG. 11, the movable element 5a pushes the slider 19 via the push rod 14. Consequently, the roller 25 falls off the upper side of the cam surface 19a, and the latch rod 22 gets into the latch hole 26 of the upper lack 11 to lock the sliding doors 1, 2. At the same time, the guide fitting 18 pushes the pull fitting 15 to engage the engagement protrusion 19b. Incidentally, to open the sliding doors 1, 2 in a case of emergency, a handle 27 in FIG. 9 is rotated 90° to pull up the latch rod 22 via a cable wire 28 to forcibly unlock the sliding doors 1, 2.
In was found that the above described side sliding door apparatus for the electric railcar disclosed in Japanese Patent Publication No. 2000-142392 has problems as described below.
The right and left sliding doors are connected to each other via the direction changing mechanism, and one actuator drives the two sliding doors. For this reason, when the actuator breaks down, the two sliding doors can not open and close, making it impossible to use the entrance.
When the sliding doors are opened, the actuator is slightly moved in the opening direction to unlock the sliding doors. For this reason, if the actuator accidentally moves in the opening direction even slightly while the electric railcar is running, there is a possibility that the sliding doors may be opened.
It is therefore an object of the present invention to improve the safety in a case where the actuator for the sliding doors breaks down or has a failure.
Further objects and advantages of the invention will be apparent from the following disclosure of the invention.